Synchronizing a swiveling three-dimensional ultrasound display with an oscillating object

ABSTRACT

An ultrasound image display method and System for a two-dimensional monitor ( 40 ) that synchronizes a swiveling or rotating volumetrically rendered three-dimensional ultrasound image ( 76 ) with the oscillation of an oscillating ultrasound object ( 72 ), such as a beating heart or breathing lung. The invention includes swiveling instructions for repetitively swiveling the volumetric ultrasound image ( 76 ) in three-dimensional space. Oscillation frequency measuring instructions ( 108 ) measure the oscillating ultrasound object&#39;s oscillation frequency. Synchronization instructions ( 118 ) synchronize a repetitive rotation of the object with the oscillation frequency such that at a predetermined point the beginning of a rotation repetition ( 110 ) coincides with the beginning of an oscillation. The volumetric ultrasound image display ( 76 ) provides the options of a live display, a variably static display, and pre-recorded display capable of continuous replay.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser.No. 60/475,300 filed Jun. 3, 2003, which is incorporated herein byreference.

The present invention relates to ultrasound systems and their methods ofoperation and, in particular, to a method and system for synchronizing aswiveling or rotating three-dimensional ultrasound image withoscillations of an oscillating ultrasound object.

Diagnostic ultrasound equipment transmits sound energy into the humanbody and receives signals reflecting off tissue and organs such as theheart, liver, kidney, etc. Blood flow patterns are obtained from Dopplershifts or shifts in time domain cross correlation functions due to bloodcell motion. These produce reflected sound waves and may be generallydisplayed in a two-dimensional format known as color flow imaging orcolor velocity imaging. Generally, the amplitudes of reflectedcomponents for structures such as the heart or vessel walls have lowerabsolute velocities and are 20 dB to 40 dB (10-100 times) larger thanreflected components due to blood cells.

In general, an ultrasound system emits pulses over a plurality of pathsand converts echoes received from objects on the plurality of paths intoelectrical signals used to generate ultrasound data from which anultrasound image can be displayed. The process of obtaining the raw datafrom which the ultrasound data is produced is typically termed“scanning,” “sweeping,” or “steering a beam”.

Real-time sonography refers to the presentation of ultrasound images ina rapid sequential format as the scanning is being performed. Scanningis either performed mechanically (by physically oscillating one or moretransducer elements) or electronically. By far, the most common type ofscanning in modern ultrasound systems is electronic wherein a group oftransducer elements (termed an “array”) arranged in a line are excitedby a set of electrical pulses, one pulse per element, timed to constructa sweeping action.

One of the most requested features on ultrasound systems is the abilityto present an image having the appearance of a three-dimensional object.Such an image is produced from a three-dimensional data matrix. Thisvolume of data is processed to create an image for display on atwo-dimensional surface that has the appearance of beingthree-dimensional. Such processing is typically referred to as arendering.

While some three-dimensional optimized ultrasound systems are available,most commercial ultrasound systems today display only planartwo-dimensional images, acquiring scan data from one-dimensional arrayprobes. The SONOS 5500 sold by PHILIPS MEDICAL SYSTEMS, is one exampleof one such system. Some commercial systems, including the SONOS 5500,can generate three-dimensional ultrasound images with the help of“off-line” post-processing. To do this, sequences of regularly spacedplanar two-dimensional sweeps are collected as the position of the probeis translated or rotated in some way between scan frames.Post-processing manipulation reconstructs three-dimensional data setsusing acquired position information for each two-dimensional scan plane.The resulting three-dimensional data sets are displayed as renderedimages, typically on a separate workstation, using any of variouswell-known, computation-intensive rendering techniques. Furthermore, thereal-time rendering and display workstation may be integrated with theultrasound scanner into one system; for example VOLUMETRICS, Inc.,produces such a system.

In both true three-dimensional volumetric ultrasound systems andtwo-dimensional ultrasound systems that produce three-dimensionalimages, it is necessary to have an effective way to display theresulting three-dimensional ultrasound images. Unfortunately, the mostcommon way of displaying ultrasound images is through a computermonitor, which generally is a two-dimensional flat screen. On atwo-dimensional computer monitor display, the three-dimensionalproperties can be lost due to a variety of factors. One such factor isthe occlusion or obstruction of portions of objects along the viewer'sline of sight. Because of visual occlusion, very important aspects of anultrasound image may be blocked from view. Such can result in a lessthan complete understanding of the information being displayed by thethree-dimensional ultrasound image.

Another problem with the display of three-dimensional ultrasound imageson a two-dimensional computer monitor relates to the phenomenon thatsome objects simply look differently when displayed as three-dimensionalultrasound images. Because of the need to develop a more completeunderstanding of what such a system is actually displaying, simplyshowing the three-dimensional ultrasound image on a two-dimensionalcomputer monitor is inadequate for many diagnoses. Without the abilityto manipulate the image in some way, it is far more likely that thevolumetric ultrasound image will not convey to the viewer all of thepossibly important information that exists in the image.

In accordance with the present invention, a method and system forsynchronizing a swiveling three-dimensional ultrasound display with anoscillating ultrasound object is provided that substantially eliminatesor reduces the disadvantages and problems associated with priorultrasound image system displays.

According to one aspect of the present invention, there is provided amethod for displaying a three-dimensional ultrasound image of anoscillating ultrasound object that includes the steps of forming avolumetric ultrasound image of the oscillating ultrasound object. Thevolumetric ultrasound image displays the oscillation of the oscillatingultrasound object The method swivels or rotates the volumetricultrasound image from a beginning aspect through a rotation or swivelcycle. The process further synchronizes a beginning of the swivel cycleof the volumetric ultrasound image to coincide with a particular phaseof an oscillation of the oscillating ultrasound object.

A technical advantage of the present invention is that it significantlyimproves the perception of a three-dimensional volumetric ultrasoundimage on a two-dimensional display or monitor by presenting to theviewer a variable display. The variable display allows the viewer to seeaspects of the volumetric ultrasound image that may be otherwiseoccluded or blocked from view due to the two-dimensional nature of thedisplay. A further technical advantage of the present invention includesthe ability to coincide the beginning of a swivel cycle with thebeginning of an oscillation of the oscillating ultrasound object. Forexample, an oscillating ultrasound object may be a human heart for whicha physician desires to perform an ultrasound analysis. An ultrasoundimaging system of the present invention, for example, can present a fullvolumetric or three-dimensional image of the beating human heart. Thethree-dimensional display, to enhance the physician's ability to extractthe full benefit of the volumetric rendering of the beating human heart,swivels the ultrasound heart image according to a period thatcorresponds to the heart beat rate. By synchronizing the swivel periodwith the heart beat rate, a continuous, more readily analyzed displayresults. The benefits of such an improved display may be a more completeunderstanding of the heart's functioning. This more completeunderstanding will increase the likelihood of an accurate diagnosis ofany associated heart malady.

A still further technical advantage of the present invention is that ofsynchronizing the swivel period with the oscillation rate of theoscillating ultrasound object to occur without additional equipment orsignificant system modification expenditures. By determining the framerate for the ultrasound image, the total swivel cycle time, and theperiod of the oscillation, the present invention makes it possible topresent the synchronized swivel display and ultrasound objectoscillation as an integrated presentation. The presentation may be, atthe viewer's discretion, that of a recorded image, a static image thatis variably controllable, and a live image. The variably controllablemode appears as a paused or frozen video image, which image iscontrollable by a track ball or similar input device.

Other technical advantages are readily apparent to one skilled in theart from the following figures, description, and claims.

For a more complete understanding of the present invention andadvantages thereof, reference is now made to the following descriptionwhich is to be taken in conjunction with the accompanying drawings inwhich like reference numbers indicate like features and wherein:

FIG. 1 is a diagram illustrating the use of an ultrasound diagnosticsystem that may use the present invention;

FIG. 2 is a block diagram of an ultrasound system in accordance with thepreferred embodiment of the present invention;

FIG. 3 shows conceptually the process of the present invention beginningwith ultrasound propagation and continuing through to display of avolumetric ultrasound image on a computer monitor;

FIG. 4 portrays the challenges of creating a two-dimensional image froma three-dimensional object, which process the present inventionaddresses;

FIG. 5 provides an exemplary flow diagram for the synchronizationprocess of the present invention;

FIGS. 6A through 6H show samples of the frames an ultrasound imagingsystem may display of an oscillating ultrasound object; and

FIGS. 7A through 7G relate to the synchronization of an ultrasound imageswivel display with the oscillating object according to the teachings ofthe present invention.

The preferred embodiment of the present invention and its advantages arebest understood by referring to FIGS. 1 through 7G of the drawings, likenumerals being used for like and corresponding parts of the variousdrawings.

FIG. 1 shows a simplified block diagram of an ultrasound imaging system10 that may use the concepts presented in accordance with the preferredembodiment of the present invention. It will be appreciated by those ofordinary skill in the relevant arts that ultrasound imaging system 10,as illustrated in FIG. 1, and the operation thereof as describedhereinafter is intended to be generally representative of such systemsand that any particular system may differ significantly from that shownin FIG. 1, particularly in the details of construction and operation ofsuch system. As such, ultrasound imaging system 10 is to be regarded asillustrative and exemplary and not limiting as regards the inventiondescribed herein or the claims attached hereto.

In certain circumstances, when it is desirable that a piece of hardwarepossess certain characteristics, these characteristics are describedmore fully in the following text. The required structures for a varietyof these machines may appear in the description given below. Machineswhich may be modified in accordance with the teachings of the presentinvention include those manufactured by such companies as PHILIPSMEDICAL SYSTEMS INTERNATIONAL, GE MEDICAL SYSTEMS, and SIEMANS MEDICALSYSTEMS, as well as other manufacturers of ultrasound equipment.

Ultrasound imaging system 10 generally includes ultrasound unit 12 andconnected transducer 14. Transducer 14 includes a receiver 16.Ultrasound unit 12 has integrated therein a transmitter 18 andassociated controller 20. Controller 20 provides overall control of thesystem by providing timing and control functions. As will be discussedin detail below, the control routines include a variety of routines thatmodify the operation of receiver 16 so as to produce a volumetricultrasound image as a live real-time image, a previously recorded image,or a paused or frozen image for viewing and analysis. Ultrasound unit 12is also provided with imaging unit 22 for controlling the transmissionand receipt of ultrasound, and image processing unit 24 for producing adisplay on a monitor (See FIG. 2). Image processing unit 24 containsroutines for rendering a three-dimensional image.

During freehand imaging, a user moves transducer 14 over subject 25 in acontrolled motion. Ultrasound unit 12 combines image data produced byimaging unit 22 with location data produced by the controller 20 toproduce a matrix of data suitable for rendering onto a monitor (See FIG.2). Ultrasound imaging system 10 integrates image rendering processeswith image processing functions using general purpose processors andPC-like architectures. On the other hand, use of ASICs to perform thestitching and rendering is possible.

FIG. 2 is a block diagram 30 of an ultrasound system in accordance withthe preferred embodiment of the present invention. The ultrasoundimaging system shown in FIG. 2 is configured for the use of pulsegenerator circuits, but could be equally configured for arbitrarywaveform operation. Ultrasound imaging system 10 uses a centralizedarchitecture suitable for the incorporation of standard personalcomputer (“PC”) type components and includes transducer 14 which, in aknown manner, scans an ultrasound beam, based on a signal from atransmitter 28, through an angle. Backscattered signals, i.e., echoes,are sensed by transducer 14 and fed, through receive/transmit switch 32,to signal conditioner 34 and, in turn, to beamformer 36. Transducer 14includes elements, preferably configured as an electronically steerabletwo-dimensional array. Signal conditioner 34 receives backscatteredultrasound signals and conditions those signals by amplification andforming circuitry prior to their being fed to beamformer 36. Withinbeamformer 36, ultrasound signals are converted to digital values andare configured into “lines” of digital data values in accordance withamplitudes of the backscattered signals from points along an azimuth ofthe ultrasound beam.

Beamformer 36 feeds digital values to application specific integratedcircuit (ASIC) 38 which incorporates the principal processing modulesrequired to convert digital values into a form more conducive to videodisplay that feeds to monitor 40. Front end data controller 42 receiveslines of digital data values from beamformer 36 and buffers each line,as received, in an area of buffer 44. After accumulating a line ofdigital data values, front end data controller 42 dispatches aninterrupt signal, via bus 46, to shared central processing unit (CPU)48, which may be a MOTOROLA PowerPC. CPU 48 executes control procedures50 including procedures that are operative to enable individual,asynchronous operation of each of the processing modules within ASIC 38.More particularly, upon receiving an interrupt signal, CPU 48 feeds aline of digital data values residing in buffer 42 to random accessmemory (RAM) controller 52 for storage in random access memory (RAM) 54which constitutes a unified, shared memory. RAM 54 also storesinstructions and data for CPU 48 including lines of digital data valuesand data being transferred between individual modules in ASIC 38, allunder control of RAM controller 52.

Transducer 14, as mentioned above, incorporates receiver 16 thatoperates in connection with transmitter 28 to generate locationinformation. The location information is supplied to (or created by)controller 20 which outputs location data in a known manner. Locationdata is stored (under the control of the CPU 48) in RAM 54 inconjunction with the storage of the digital data value.

Control procedures 50 control front end timing controller 45 to outputtiming signals to transmitter 28, signal conditioner 34, beamformer 36,and controller 20 so as to synchronize their operations with theoperations of modules within ASIC 38. Front end timing controller 45further issues timing signals which control the operation of the bus 46and various other functions within the ASIC 38.

As aforesaid, control procedures 50 configure CPU 48 to enable front enddata controller 44 to move the lines of digital data values and locationinformation into RAM controller 52 where they are then stored in RAM 54.Since CPU 48 controls the transfer of lines of digital data values, itsenses when an entire image frame has been stored in RAM 54. At thispoint, CPU 48 is configured by control procedures 50 and recognizes thatdata is available for operation by scan converter 58. At this point,therefore, CPU 48 notifies scan converter 58 that it can access theframe of data from RAM 54 for processing.

To access the data in RAM 54 (via RAM controller 52), scan converter 58interrupts CPU 48 to request a line of the data frame from RAM 54. Suchdata is then transferred to buffer 60 of scan converter 58 and istransformed into data that is based on an X-Y coordinate system. Whenthis data is coupled with the location data from controller 20, a matrixof data in an X-Y-Z coordinate system results. A four- (4-) dimensionalmatrix may be used for 4-D (X-Y-Z-time) data. This process is repeatedfor subsequent digital data values of the image frame from RAM 54. Theresulting processed data is returned, via RAM controller 52, into RAM 54as display data The display data is stored separately from the dataproduced by beamformer 36. CPU 48 and control procedures 50, via theinterrupt procedure described above, sense the completion of theoperation of scan converter 58. Video processor 64, such as theMITSUBISHI VOLUMEPRO series of cards, interrupts CPU 48 which respondsby feeding lines of video data from RAM 54 into buffer 62, which isassociated with the video processor 64. Video processor 64 uses videodata to render a three-dimensional volumetric ultrasound image as atwo-dimensional image on monitor 40. Further details of the processingof four dimensional cardiac data may be found in U.S. Pat. No.5,993,390.

FIG. 3 shows conceptually the process of the present invention,beginning with ultrasound propagation and continuing through to thedisplay of a volumetric ultrasound image on computer monitor 40. In theexample shown in FIG. 3, there are slices 66 conjoined at single apex68, but otherwise separated. Each of scan lines 70 in slices 66 has amatching (or “indexed”) scan line in the other slices. Preferably, scanlines 70 with the same lateral position are matched across the set ofslices. One way to accomplish this is to index each of the scan lines ina slice by numbering them in sequence. Then scan lines 70 having thesame index value can be easily matched.

To render a volumetric three-dimensional image, data points on each ofsets of matched scan lines 70 are linearly combined using an additionroutine. In other words, each slice in the set of slices is accumulatedin the elevation direction to produce an aggregate slice for subsequentdisplay. Preferably, but not necessarily, the data points in each sliceare weighted, for example, on a line-by-line basis by using a multiplyand accumulate routine (also known as a “MAC routine”).

FIG. 3 further illustrates the processing of ultrasound data, forexample of human heart 72, using volumetric ultrasound processing forwhich the present invention has particular beneficial application. Inone embodiment, the present invention has particularly beneficial usewith a live, three-dimensional ultrasound architecture thatinstantaneously processes data from slice 66 arising from the use oftransducer 14 to produce voxel matrix 74 of data Voxel matrix 74,through the use a powerful supercomputer architecture such as that ofthe SONOS 7500 System manufactured by Philips Medical Systems, processeswithin a small amount of time, nominally 50 milliseconds, streamingthree-dimensional ultrasound data. This processed ultrasound data maythen appear on a monitor 40 screen to show in real-time, oscillatingultrasound object 76.

The three-dimensional system such as the SONOS 7500 with which thepresent invention operates uses transducer 14, which includes a3000-element array, and associated microprocessors that preprocess datausing an advanced, yet PC-based, computing platform, as well as specialsoftware that allows interactive image manipulation and an easy-to-useoperator interface. The 3000-element array captures data about anultrasound object, such as the heart, as a volume. By combining atansducer crystal that is etched to have the necessary number ofcrystals with a microprocessing circuit that efficiently triggers thetransducer elements, the ultrasonic imaging system with which thepresent invention operates harnesses the computing power of more than150 computer boards. Further details of such an array andmicroprocessors are described in U.S. Pat. Nos. 5,997,479; 6,013,032;and 6,126,602.

The processing architecture includes both hardware and software thatallows real-time generation of volume data. This PC-based technologysupports instantaneous display of three-dimensional images. With thistechnology, the ultrasound imaging system applies the 3000 channels tothe SONOS 7500 mainframe beamformer for scanning in real time.Three-dimensional scan converter 58 processes at a rate of over 0.3giga-voxels per second to produce image 76 from voxel matrix 74.

The present embodiment of the invention, therefore, may be employed in athree-dimensional live ultrasound imaging and display process to enhanceknown echocardiography analysis and diagnosis. The system with which thepresent invention may operate has the ability to generate and displaythree-dimensional images of a beating heart an instant after the dataare acquired. However, the present invention may also operation withother, near-real-time three-dimensional systems which may need severalseconds to acquire the data and additional time to reconstruct it as athree-dimensional ultrasound display. In such systems, data acquisitionleading to three-dimensional ultrasound images of the heart may be gatedfor electrocardiogram and respiration analysis and diagnosis.

The system with which the present invention preferably operates deliversa full-volume view of the heart that can be rotated to allow theoperator to see cardiac anatomy from several perspectives. Images canalso be cropped to obtain cross-sectional pictures of complex anatomicalfeatures such as heart valves. The preferred ultrasound system for usingthe present invention can also provide information about a patient'sheart size, shape, and anatomic relationships. Such a system isattractive to a wide range of medical environments from the communityhospital and university echo lab to private offices. Thethree-dimensional capability of such a system allows a better appraisalof the correlation between valves, chambers, and vessels in the heart.

The live, volumetric ultrasound system with which the present inventionpreferably operates provides improved visualization of complex anatomicfeatures, particularly in pediatrics. Typically in pediatrics,cardiologists spend quite a bit of time looking at varioustwo-dimensional planes, trying to link one part of the heart to another.Volume rendering by a system of the present invention may lead toimproved, faster assessment of the pediatric heart, because physicianscan better visualize the heart and surrounding structures.

Volumetric rendering coupled with the swiveling display of the presentinvention, permits a viewer to manipulate the data set in space, rotatethe image while maintaining a chosen perspective, and thereby provideclarity to the structural orientation of the pathology. The combinationof controllable live, volumetric ultrasound imaging and the synchronizedswiveling or rotating provided by the present invention enhances thelikelihood of obtaining the view most likely to provide the right answermore quickly. This is because the viewer has information that he wouldotherwise not possess.

The combination of synchronized swiveling display and volumetricrendering has demonstrated several other potential advantages during theearly testing. The present invention may allow more accurate assessmentof valvular function. The ability to deliver in real-time many andchanging two-dimensional displays of volumetrically renderedthree-dimensional images may be helpful during catheter guidance.Moreover, the enhanced display of the present invention may provideperformance improvements when assessing regional and global cardiacfunctions, as well as improve productivity by shortening the time fordata acquisition and interpretation.

FIG. 4 introduces the challenge of using the volumetrically-renderedthree-dimensional ultrasound image using a two-dimensional screen suchas that of computer monitor 40. As FIG. 4 depicts, voxel matrix 74 hasbeen created as a true volumetric rendering of an ultrasound object,such as beating human heat 72. Monitor 40 includes an array of pixels 78which are differentially energized and controlled by ultrasound imagingsystem 10. Without the process of the present invention, occlusion andimperfections associate with attempting to convey three-dimensional dataform voxel matrix 74 on two-dimensional monitor 40 as image 80. This mayprevent viewer 82 from appreciating the benefits of the processing anddata capture which ultrasound imaging system 10 can provide.

The present invention, therefore, provides a process that overcomes thedepth perception and other related problems of volumetric imaging. Toovercome the depth perception problem, the present invention takes intoconsideration the fact that, because the image is a fullyvolumetrically-rendered ultrasound image, it is possible to variablydisplay the image from a wide variety of angles on monitor 40. Moreover,the present invention acknowledges that, with an oscillating object,such as beating heart 72, it is possible to further enhance thethree-dimensional perception of the oscillating ultrasound object.Accordingly, the present invention provides a process for both takingadvantage of the many angles in three-dimensional space through which anultrasound object may be viewed and the fact that some ultrasoundobjects, by their very nature, oscillate, vibrate, or otherwiserepeatedly or cyclically move. This combination results in thesynchronization of the swivel or rotation cycle in the volumetricultrasound image with the oscillation or beating movement of theultrasound object.

FIG. 5, therefore, provides an exemplary flow diagram for thesynchronization process of the present invention. In brief, the methodincludes the steps of forming a volumetric ultrasound image of anoscillating ultrasound object. The volumetric ultrasound image displaysthe oscillation of the oscillating ultrasound object. In this embodimentthe display repetitively rotates the volumetric ultrasound image from abeginning aspect through a swivel or rotation cycle, with the swivel orrotation returning to the beginning aspect. The process synchronizes abeginning of the repetitive rotation of the volumetric ultrasound imageto coincide with the beginning of an oscillation of the oscillatingobject.

The process 100 begins on a system such as the SONOS 7500, bydetermining at step 102 if the viewer has enabled the system's swivelingaction display. Only if the swivel process is enabled will theultrasound image system employ the synchronization process. Thesynchronization process 100 begins with calculating the number of timesan oscillation should be replayed for the given swivel cycle at step104. This includes determining the frame rate in hertz or frames persecond for the given ultrasound display system at step 106. Then, theprocess obtains the number of frames (i.e., single volumes) contained inan oscillation of the oscillating ultrasound object at step 108. Theprocess then calculates the total time in seconds that it would take torepeat one oscillation at step 110. This is done by dividing the numberof frames in an oscillation by the frame rate in frames per second ofthe ultrasound display system.

The process then calculates how many times to repeat the oscillationdisplay for a single three-dimensional swivel cycle at step 112. In thepreferred embodiment a nominal period of five seconds has proveneffective and simple to generate for the swivel cycle period. At thisstep, some rounding may occurs in this process as through the use ofknown rounding functions that may exist in the appropriate computerlanguage in use for the process. In essence, this calculation involvesdividing the value of the number of frames for the oscillation cycleinto the number of frames for the swivel cycle. To assure that thedisplay of the swivel cycle terminates at the end of the lastoscillation in the display, the period of the swivel cycle is set toterminate at the end of the last oscillation occurring in during theswivel period.

For example, if a beating heart beats at a rate of 0.7 second per beat,then seven of such beats will occur in 4.9 seconds. Therefore, to havethe end of the last beat occur at the end of the swivel cycle, theswivel period is set to 4.9 seconds. At 4.9 seconds, therefore, thevolumetric ultrasound display will return to the same beginning aspect.In the present embodiment there are three modes where thethree-dimensional swivel display may be active. These include a replaymode, a freeze mode, and a live mode. Other names for these modes maybe, for example, the cine loop mode, the pause mode or the acquiringmode. In a live mode, a continuous stream of new volumetric ultrasounddata is displayed on ultrasound imaging system 10. Also, during thisoperational mode, the present invention may collect data that may belater displayed. In the freeze mode, either live or replay mode isstopped for the display. This is similar to the pause function of avideo cassette recorder. The variably controllable mode appears as apaused or frozen video image, which image is controllable by a trackball or similar input device. In the replay mode, a recordedvolumetrically rendered ultrasound image is played from the memoryassociated with ultrasound imaging system 10.

Process 100 of the present invention, therefore, determines in which ofthese modes the viewer has directed ultrasound imaging system 10 tooperate at step 114. If the system has been directed to operate in thereplay mode, as tested by query 116, then process flow goes to step 118.Otherwise, query 120 tests whether the viewer has directed ultrasoundimaging system 10 to operate in the freeze mode. Is so, then the processflow goes to step 122, where the ultrasound image rendering rate of 10Hz is established. Otherwise, process 100 tests whether the viewer hascontrolled ultrasound imaging system 10 to operate in the live mode atquery 124. If so, process control goes to step 126, where a nominalswivel cycle length is established. Otherwise, the present embodiment ofthe invention controls process flow to return to query 116, but now withthe default that the viewer has directed ultrasound system 10 to operatein the replay mode.

In the replay mode, step 118 of the process calculates the number offrames in an oscillation. Step 128 determines how many times anoscillation should be played in a swivel cycle. This is determined bycalculating the total number of complete oscillations that may fitwithin a set swivel period. So, for example, an oscillation lasting 0.7seconds may be completely repeated in a swivel period of five (5)seconds a total of seven (7) times, with a remainder of one (1) second.Or, equivalently, in 4.9 seconds exactly seven (7) complete oscillations(i.e., seven (7) complete periodic heart cycles) will occur. Further,the process calculates, at step 130, the number of frames required toachieve the desire swivel period duration. This is done simply bymultiplying the number of frames per oscillation by the number ofoscillations in the swivel period. This determines the number of framesto use for the swivel. So, for example, if the volumetric ultrasounddisplay rendered at a rate of 20 Hz, then in an oscillation period of0.7 seconds there would be 14 (=20 Frames/sec×0.7 sec/oscillation)frames per oscillation. This would call for 98 (=14 frames/oscillation×7oscillations/swivel period) frames to be used in the swivel period.Accordingly, from the beginning aspect of the volumetric ultrasoundimage through the entire swivel range and back to the beginning aspectshould use 98 frames from ultrasound imaging system 10 on monitor 40.This will assure that all swivel periods begin and end at the sameaspect. Furthermore, the swivel period is divided into 98 phases, suchthat each phase, corresponding to a unique frame, is displayed at aslightly different viewing angle.

In the live mode, the ultrasound system acquires live ultrasound data.This may use a default number of frames for the live data at step 126.This would permit a simplification of the display when actuallyacquiring live info. Alternatively, the number of frames observed for agiven oscillation can be used for the purpose of providing a volumetricultrasound image display that achieves the same beginning and endingaspects as described above.

In the pause mode, i.e., during either the live or cine loop mode beingpaused, the display will be presented in a period of 10 Hz. This may bea variably static display through which the viewer has control of theaspect angle of the volumetric ultrasound image. The swivel display maybe set at five (5) seconds with a refresh interval of 100 milliseconds,for example. Also, in the freeze mode, the system determines where touse the nominal swivel period as is used in the live mode at step 132.

The process further controls the three-dimensional swivel angle at step134. For example, in the present embodiment the horizontal range may be+/−50 degrees with a vertical angle of 0 degrees. Moreover, at step 136,the present embodiment provides a way to smooth both the swivel displayand the appearance of the oscillation on monitor 40. There may be otherways of changing the swivel angle and display. Moreover, the process ofFIG. 5 is intended to be only exemplary, for there may be many differentways of implementing the novel concepts of the present invention whiledeviating from the precise steps of the FIG. 5 flowchart.

In order to demonstrate the benefits of the present inventions FIGS. 6Athrough 6H and 7A through 7G demonstrate the synchronization of anultrasound image swivel display with the oscillating object according tothe teachings of the present invention. In FIGS. 6A through 6H, a seriesof volumetric ultrasound images of a beating human heart 72 appear as anoscillating ultrasound object. In this example, human heart 72 beats ata rate of 0.7 seconds per beat. Thus, if ultrasound imaging system 10renders a volumetric ultrasound image at a rate of 20 Hz, then each beatconsumes 14 frames. Accordingly and showing only the relevantodd-numbered frames, FIG. 6A shows a volumetric ultrasound image of theheart at a Frame 1 occurring at 0.00 sec, FIG. 6B an image at a Frame 3,which occurs at 0.15 sec, FIG. 6C shows the Frame 5 occurring at 0.25sec, on to FIG. 6G of the Frame 13 occurring at 0.65 seconds. Note thatFIG. 6H shows Frame 15, which is similar to Frame 1 of FIG. 6A, sincethe human heat 72 has begun a new oscillation or beat. However, noticefurther that, since image 76 is swiveling, the aspect or view of image76 has changed. Thus, FIGS. 6A through 6G would show a completeoscillation or beat for the beating human heart, with FIG. 6H showingthe beginning of a new oscillation or beat.

FIGS. 7A through 7G relate to the synchronization of an ultrasound imageswivel display with the oscillating object according to the teachings ofthe present invention. Thus, FIGS. 7A through 7G show progressive imagesof the human heart through a single swivel or rotation period. Based onthe period, 0.7 seconds, for a complete heart beat, and the initiallynominal swivel period of five (5) seconds, a total of seven (7)(=(5.0seconds/swivel period)/(0.7 seconds/oscillation)) oscillations or heatbeats are called for in the swivel period. Thus, FIG. 7A shows thebeginning heart beat of the seven heart beats concluding at 0.7 sec.FIG. 7B shows the second heart beat concluding at 1.4 sec. Continuing at0.7 second intervals, the swivel rotation concludes at FIG. 7G whichshows the final heart beat at 4.9 sec.

Note that in the progressive views of FIGS. 7A through 7G, while theaspect of the ultrasound object changes, the stage of the ultrasoundobject in its oscillation does not change as significantly. The previousFIGS. 6A through 6H, however, show that the appearance of the heartvalve changes significantly during its beating. Note that the phenomenaof the heart not changing significantly from the beginning aspect of theswivel period and the ending aspect of the swivel period and thepositions of the beginning aspect and ending aspect being essentiallythe same provides for significant flexibility in both recording andplaying back recorded volumetric ultrasound images.

One benefit of the present invention is that existing hardware andsoftware can be easily modified to produce the required images. Forexample, using controls which are already available on the SONOS 7500,images in accordance with the present preferred embodiment can beproduced without any changes to the hardware.

Accordingly, it is to be understood that the embodiments of theinvention herein described are merely illustrative of the application ofthe principles of the invention. Reference herein to details of theillustrated embodiments is not intended to limit the scope of theclaims, which themselves recite those features regarded as essential tothe invention.

1. A method for displaying three-dimensional ultrasound image datarepresenting an oscillating object, comprising the steps: forming avolumetric ultrasound image of an oscillating object, said volumetricultrasound image for displaying the oscillation of said oscillatingobject; rotating the volumetric ultrasound image from a beginning aspectthrough a rotation period; synchronizing a beginning of the rotationperiod of the volumetric ultrasound image to coincide with the beginningof an oscillation of the oscillating object; and displaying on atwo-dimensional display a three-dimensional perception of saidvolumetric ultrasound image of said oscillating object.
 2. The method ofclaim 1, wherein said rotating step comprises the step of swiveling thevolumetric ultrasound image from a beginning swivel aspect through aswivel cycle, said swivel cycle returning the volumetric ultrasoundimage of the oscillating object to said beginning swivel aspect.
 3. Themethod of claim 1 further comprising the step of controllably displayingsaid volumetric ultrasound image from a plurality of three-dimensionaldirections.
 4. The method of claim 1, further comprising the step offorming a volumetric ultrasound image of a beating heart, wherein saidoscillation corresponds to the beating of said beating heart.
 5. Themethod of claim 4, further comprising the step of controllablydisplaying said beating heart as a real-time volumetrically renderedultrasound image.
 6. The method of claim 4, further comprising the stepof controllably displaying said beating heart as a previously recordedvolumetrically rendered ultrasound image.
 7. The method of claim 4,further comprising the step of controllably displaying said beatingheart as a static volumetrically rendered ultrasound image.
 8. Themethod of claim 7, wherein the static volumetrically rendered ultrasoundimage comprises a variably-controllable, static, volumetrically renderedultrasound image, the method further comprising displaying saidvariably-controllable, static, volumetrically rendered ultrasound imageof the beating heart such that the beginning aspect of thevariably-controllable, static, volumetrically rendered ultrasound imageof said beating heart corresponds to a stage of said beating heart atsome point in the beating.
 9. The method of claim 8 further comprisingthe step of volumetrically rendering said variably-controllable, static,volumetrically rendered ultrasound image of said heart at a rate of notless than 10 Hz.
 10. The method of claim 8 further comprising the stepof controllably changing a view of the variably-controllable, static,volumetrically rendered ultrasound image of said heart using athree-dimensional positioning control system.
 11. The method of claim 1,further comprising the steps of: forming said volumetric ultrasoundimage of the oscillating object as a real-time volumetric ultrasoundimage; and recording said rotating volumetric ultrasound image of saidoscillating object for forming a recorded volumetric ultrasound imagehaving a property that repeated continuous playing of said recordingsappear as a continuous oscillating display of said oscillating object.12. A system for displaying a three-dimensional ultrasound image of anoscillating object, the system comprising: a processing device includingat least one processor and at least one memory device storinginstructions to be executed by the at least one processor, theprocessing device being configured to execute an algorithm including:forming a volumetric ultrasound image of an oscillating object, saidvolumetric ultrasound image for displaying the oscillation of saidoscillating object; rotating the volumetric ultrasound image from abeginning aspect through a rotation; synchronizing a beginning of therotation of the volumetric ultrasound image to coincide with thebeginning of an oscillation of the oscillating object; and displaying ona two-dimensional display a three-dimensional perception of saidvolumetric ultrasound image of said oscillating object.
 13. The systemof claim 12, wherein the algorithm executed by the processing devicefurther comprises swiveling the volumetric ultrasound image from abeginning swivel aspect through a swivel cycle, said swivel cyclereturning the volumetric ultrasound image to said beginning swivelaspect.
 14. The system of claim 12, wherein the algorithm executed bythe processing device further comprises controllably displaying saidvolumetric ultrasound image from a plurality of three-dimensionaldirections.
 15. The system of claim 12, wherein the algorithm executedby the processing device further comprises forming a volumetricultrasound image of a beating heart, wherein said oscillationcorresponds to the beating of said beating heart.
 16. The system ofclaim 15, wherein the algorithm executed by the processing devicefurther comprises controllably displaying said volumetric ultrasoundimage of the beating heart as a real-time volumetrically renderedultrasound image.
 17. The system of claim 15, wherein the algorithmexecuted by the processing device further comprises controllablydisplaying said volumetric ultrasound image of the beating heart as apreviously recorded volumetrically rendered ultrasound image.
 18. Thesystem of claim 15, wherein the algorithm executed by the processingdevice further comprises controllably displaying said volumetricultrasound image of the beating heart as a static volumetricallyrendered ultrasound image.
 19. The system of claim 18, wherein thestatic volumetrically rendered ultrasound image comprises avariably-controllable, static volumetrically rendered ultrasound image,the algorithm further comprising displaying said variably-controllable,static, volumetrically rendered ultrasound image of the beating heartsuch that the beginning aspect of the variably-controllable, static,volumetrically rendered ultrasound image of the image of said beatingheart corresponds to a stage of said beating heart at some point in thebeating.
 20. The system of claim 19, wherein the algorithm executed bythe processing device further comprises volumetrically rendering saidvariably-controllable, static, volumetrically rendered ultrasound imageof the of said heart at a rate of not less than 10 Hz.
 21. The system ofclaim 19, wherein the algorithm executed by the processing devicefurther comprises controllably changing a view of saidvariably-controllable, static, volumetrically rendered ultrasound imageof the of said heart using a three-dimensional positioning controlsystem.
 22. The system of claim 12, wherein the algorithm executed bythe processing device further comprises: forming said volumetricultrasound image of the oscillating object as a real-time volumetricultrasound image; and recording said rotating volumetric ultrasoundimage of said oscillating object for forming a recorded volumetricultrasound image having a property that repeated continuous playing ofsaid recordings appear as a continuous non-repetitive display of saidoscillating object.
 23. A tangible. processor-readable, storage mediumstoring instructions that are executable by at least one processor forforming an ultrasound image synchronizing system for displaying athree-dimensional ultrasound image of an oscillating object, said storedinstructions comprising: volumetric ultrasound image forminginstructions for forming a volumetric ultrasound image of an oscillatingobject, said volumetric ultrasound image for displaying the oscillationof said oscillating object; rotating instructions for rotating thevolumetric ultrasound image from a beginning aspect through a rotation;synchronizing instructions for synchronizing a beginning of the rotationof the volumetric ultrasound image to coincide with the beginning of anoscillation of the oscillating object; and displaying instructions fordisplaying said oscillating object on a two-dimensional display forpresenting the three-dimensional perception of said volumetricultrasound image of said oscillating object.
 24. The storage medium ofclaim 23, wherein said stored instructions further comprise: imageforming instructions for forming said volumetric ultrasound image of theoscillating object as a real-time volumetric ultrasound image; andrecording instructions for recording said rotating volumetric ultrasoundimage of said oscillating object for forming a recorded volumetricultrasound image having the property that repeated continuous playing ofsaid recordings appear as a continuous display of said oscillatingobject.
 25. A method for displaying three-dimensional ultrasound imagedata representing an oscillating object, the method comprising: forminga volumetric ultrasound image of an oscillating object, said volumetricultrasound image for displaying the oscillation of said oscillatingobject; rotating the volumetric ultrasound image from a beginning aspectthrough a rotation period; and displaying the rotating volumetricultrasound image on a display device.
 26. The method of claim 25,wherein said rotating step comprises swiveling the volumetric ultrasoundimage from a beginning swivel aspect through a swivel cycle, said swivelcycle returning the volumetric ultrasound image of the oscillatingobject to said beginning swivel aspect.
 27. The method of claim 25,further comprising controllably displaying said volumetric ultrasoundimage from a plurality of three-dimensional directions.
 28. The methodof claim 25, further comprising forming a volumetric ultrasound image ofa beating heart, wherein said oscillation corresponds to the beating ofsaid beating heart.